TYPO3 has an excellent framework for developing extensions. I'm sure things could be improved (they always can!), but compared to many other open source projects installing and uninstalling extensions in TYPO3 is dead simple and mostly safe.
The result is that there are quite a few extensions out there (we're nearing 3000) which is great. One drawback is that it's often difficult to find the right tool because of this very abundance. A rating system can help in this case. A long time ago there was the idea of a review process that would give a general quality rating to an extension. This failed because there were far more extensions than reviewers and only a couple of extensions ever got rated.
More recently, when the TYPO3 Extension Repository was overhauled, a voting system was introduced. It was not to everyone's taste, but it was thought that it would at least make it more simple for people to express their opinion than a formal review process.
Unfortunately this is failing too: people are simply not voting, or at least not enough. Me included so let me cast the first stone at myself. When thinking about it I can't come up with any good reason for not doing it, except the usual "I don't have time now, I'll do it later." Which is rather lame, isn't it? Having reached that conclusion I went on a voting spree yesterday and rated the extensions that I use and appreciate most.
I think it is a very important thing to do. Most of the time we contact extension developers only when we find a bug. We do take this opportunity to thank them for their work, of course, but we just never send those thanks spontaneously (if you do, well, great!). Apart from that there's the download count which shows that some people do use your extension. If you are in harmony with the spirit of sharing you don't absolutely need thanks to keep you going, but receiving some still does good and motivates you to further share your stuff.
So do a good deed today and vote for your favorite extensions!